Hysteroscopy involves inserting a hysteroscope, which is 3-5 mm thick, into the uterine cavity through the vagina and cervix. The internal walls of the uterus, including the anterior and posterior walls, the uterine fundus, and the entry points of the fallopian tubes, are examined directly via a monitor to check for abnormalities within the uterine cavity. If necessary, a biopsy or the use of specially designed instruments may be performed to address any identified lesions.